Playlist to queue

Solves #59 (closed)

inc/lektor/cmd.h

@@ -26,4 +26,4 @@ noreturn void lkt_cmd_parse(struct lkt_cmd_opt *opts, int argc, const char **arg
    in case of errors. */
 extern const char *executable_name;
 
-noreturn void help__(void);
+noreturn void print_help(void);